I agree it's possible, but the developed world already has sub-replacement fertility. Each additional hurdle (freezing eggs, committing to fitness, avoiding oth

I agree it's possible, but the developed world already has sub-replacement fertility. Each additional hurdle (freezing eggs, committing to fitness, avoiding other health issues, still having the desire for more children in your 50s, ...) filters away another significant fraction of the population, until what is left has no hope of replacement fertility, or even a manageably slow decline. You'll hit a population cliff, with all the pain associated with that metaphor.